How do you link to documentation via an operator
In the file  2.77/scripts/startup/bl_operators/wm.py you will find all the wm.doc_* operators, 

class WM_OT_doc_view_manual(Operator):
    """Load online manual"""
    bl_idname = "wm.doc_view_manual"
    bl_label = "View Manual"

    doc_id = doc_id
    ...


We can override this operator to call our own.  Here the doc_id is 

import bpy
from bl_operators.wm import WM_OT_doc_view_manual, doc_id

class Overide_doc_view_manual(WM_OT_doc_view_manual):
    doc_id = doc_id
    def invoke(self, context, event):
        print("Invoke")
        return {'FINISHED'}

    def execute(self, context):
        print("Online manual", self.doc_id)
        return {'FINISHED'}

def execute(self, context):
    print("Called myClass")
    return {'FINISHED'}
# lazy register
bpy.utils.register_class(Overide_doc_view_manual)